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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 11 |
| 4 | 54 |
| 5 | 330 |
| 6 | 2430 |
| 7 | 20970 |
| 8 | 207900 |
| 9 | 2331000 |
| 10 | 29189160 |
| 11 | 404044200 |
| 12 | 6129723600 |
| 13 | 101181603600 |
| 14 | 1805933329200 |
| 15 | 34664949118800 |
[1,3,11,54,330,2430,20970,207900,2331000,29189160, 404044200,6129723600,101181603600,1805933329200, 34664949118800] |